Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.148: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Structural and magnetic properties of the alternating Heisenberg spin-chain compound dichloro(2,5-dithiahexane)copper(II) — •S. Matejcek¹, E. Herrling¹, G. Fischer¹, B. Pilawa¹, and H. Henke² — ¹Physikaliches Institut, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany — ²Institut für Anorganische Chemie, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany

The one-dimensional alternating Heisenberg antiferromagnet dichloro(2,5-dithiahexane)copper(II) shows a structural phase transition at T_c≈150K. This phase transition was examined by ESR-measurements, x-ray diffraction, measurements of the static magnetic susceptibility and the specific heat. Below T_c the symmetry reduction from the monoclinic space group P2₁/n to the triclinic group P1 results in the formation of twin domains and the creation of two different kinds of spin chains. Measurements of the static magnetic susceptibility yield the exchange constants and alternation parameters J₁/k_B=−29.3K, α₁=0.76 and J₂/k_B=−27.9K, α₂=0.99 of chain 1 and 2, respectively.
The specific heat was measured in the temperature range between 10K and 200K using the method of continuous heating. The hysteretic behaviour of the phase transition was studied by measurements using different heating rates. The transition enthalpy of the structural phase transition was determined and it was proved that the low temperature phase is stable with no further phase transitions down to 10K.